British Airways has announced the cancellation of two more international flights amid fears of terrorism.

British Airways has grounded a Sunday flight to Washington D.C. and a Monday flight to Riyadh. Both were to have departed from London's Heathrow airport.

The airline made the decision following advice from the British government. The specific reason behind the cancellations has not been disclosed publicly, although the U.S. Department of Homeland Security has warned in recent weeks that it believes the al-Qaida terror network remains interested in international aviation targets.

This just the latest example of airline cancellations or delays seen here since the Christmas period nearly two months ago.

British Airways says more than 300 passengers were booked on the two grounded planes.